Conventionally, for example, percutaneous cardiopulmonary support (PCPS) is used as an extracorporeal circulation method. This percutaneous cardiopulmonary support is a method in which cardiopulmonary support is carried out through femoral artery and vein by a pump-oxygenator device (extracorporeal circulation device) in a closed circuit using a centrifugal pump and a membrane oxygenator in general. Therefore, when supply of blood to a patient is necessary during an operation or the like, an extracorporeal circulation device having a pump-oxygenator and so forth is used in order to extracorporeally circulate the blood of the patient. Furthermore, it has been known to monitor the amount of movement of oxygen and carbon dioxide in the blood that circulates by such an extracorporeal circulation device has also been made (for example, Japanese Laid-open Patent Application No. 2006-122111).
Meanwhile, such an extracorporeal circulation device has a venous-side tube that is for guiding blood of a patient from the patient to the oxygenator and couples a vein of the patient and the oxygenator. In addition, the extracorporeal circulation device also has an arterial-side tube that is for supplying blood of the oxygenator to the patient and couples the oxygenator to an artery of the patient. Furthermore, the oxygen consumption or the like of the patient who uses the extracorporeal circulation system is obtained based on information on the oxygen saturation, hemoglobin, and so forth of blood in these venous-side tube and arterial-side tube.